Databases Reference
In-Depth Information
Table 5.2
The Suppliers and Parts Database (Sample Values)—Semitemporal Version
S_SINCE
S#
SNAME
STATUS
CITY
SINCE
S1
Smith
20
London
d04
S2
Jones
10
Paris
d07
S3
Blake
30
Paris
d03
S4
Clark
20
London
d04
S5
Adams
30
Athens
d02
SP_SINCE
S#
P#
SINCE
S1
P1
d04
S1
P2
d05
S1
P3
d09
S1
P4
d05
S1
P5
d04
S1
P6
d06
S2
P1
d08
S2
P2
d09
S3
P2
d08
S4
P2
d06
S4
P4
d04
S4
P5
d05
CONSTRAINT AUG_SP_TO_S_FK
IS_EMPTY (((S_SINCE RENAME SINCE AS SS) JOIN
(SP_SINCE RENAME SINCE AS SPS)) WHERE SPS < SS);
With this example we begin to see the problem. Given a semitemporal
database like that of Table 5.2, we will probably have to state many aug-
mented foreign key constraints like this one, and we will soon begin to wish
we had some convenient shorthand for the purpose.
5.3.1.2 Queries (Semitemporal Database)
We now consider semitemporal versions of Queries 1.1 and 1.2.
